JPH08146377A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: To improve a liquid crystal display device mounted with an input device having transmissivity on a display part. CONSTITUTION: This liquid crystal display device consists of a touch switch 17 which detects the position of an input point applied with a pressure from the front surface and has transmissivity and a liquid crystal layer 13 enclosed between a first transparent substrate 11 and a second transparent substrate 12 formed thereon and has the liquid crystal display part 14 which is disposed in the lower part of this touch switch 17 and displays the position of the input point. The liquid crystal display part 14 is a liquid crystal display panel of a normally black type and displays the input point by normally impressing an electric field on the liquid crystal layer 13 of the region exclusive of the input point and selectively not impressing the electric field only to the liquid crystal layer 13A corresponding to the region of the input point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to improvement of a liquid crystal display device in which a translucent input device is mounted on a liquid crystal display portion. In recent years, lightweight and portable small personal information terminals (PDA: Pers)
As a liquid crystal display device used for an onal digital assistant) or the like, a liquid crystal display device in which a pen input device is mounted instead of the conventional keyboard input has been proposed, and the demand thereof is increasing.

[0002]

2. Description of the Related Art A conventional liquid crystal display device will be described below with reference to the drawings. 5 is a sectional view taken along line YY of FIG. The liquid crystal display device according to the conventional example is
As shown in FIG. 4, first and second transparent substrates (1, 2) having predetermined members such as transparent electrodes and alignment films (not shown) formed on their surfaces are fixed by a sealant (S1), and in between. A liquid crystal display section (4) in which liquid crystal (3) is enclosed and polarizing plates (8, 9) are attached to the upper and lower sides, and also serves as an electrode of a touch switch and has an electrically conductive ITO (not shown).
(Indium Tin Oxide) film is attached to one side of the third,
A fourth transparent substrate (5, 6), and a fourth transparent substrate (6) on the third transparent substrate (5) so that ITO films (not shown) attached to the respective transparent substrates face each other. ) Is a spacer (S
It has an analog input type resistive film type touch switch (7) arranged via 2).

This touch switch (7) is directly fixed on a polarizing plate (9) formed on the liquid crystal display section (4) for space saving, and the liquid crystal display section (4) has no touch switch. Mari White STN (Super Twisted Nematic)
) A liquid crystal display panel is used. Further, the polarizing plates (8, 9) are arranged in a positive type (crossed nicols only for TN).

According to this apparatus, a pattern such as a character or a picture is input by handwriting on the touch switch (7) with an input pen, so that the input pattern is immediately displayed on the liquid crystal display section (below the touch switch (7)). 4) Since it can be displayed on the screen, the operator can input a desired character or picture through the touch switch (7) having translucency while watching the display.

That is, as shown in FIG. 5, the operator presses a desired point on the fourth transparent substrate (6) of the touch switch (7) with an input pen (ST). Then, the third
The transparent substrate (5) and the fourth transparent substrate (6) come close to each other due to the pressure bonding force, and the ITO films (not shown) serving as electrodes formed facing each other on both sides thereof come into contact with each other.

This ITO film is evenly formed on the entire surfaces of the third and fourth transparent substrates (5, 6), and the input pen (S
When the upper and lower ITO films come into contact with each other at a point (hereinafter referred to as an input point) crimped by T), the current between the upper and lower ITO films changes. Since the current change differs depending on the input point, the position of the input point is detected by detecting the current change.

When the position of the input point thus detected is output to a drive circuit (not shown), an electric field is applied only to the liquid crystal molecules (3A) at the position of the input point as shown in FIG. Since only this liquid crystal molecule (3A) rises and no electric field is applied to the liquid crystal molecules in other regions, all of these liquid crystal molecules are in the twisted alignment state. Therefore, in the normally white type liquid crystal display unit (4), a black dot is displayed on the liquid crystal display unit (4) at the position of the input point by applying an electric field only to the liquid crystal molecules (3A) at the input point and rising. It

When the operator inputs an input pattern such as a line, a character, or a picture by repeating the above operation for each input point, the pattern is displayed under the touch switch (7) as shown in FIG. It is displayed in black on the liquid crystal display (4). The operator touches the transparent touch switch (7).
You can check the display via. Such a liquid crystal display device is miniaturized for mounting on a PDA or the like,
Lighter and thinner are required. For example, a film LCD using a thin film as a transparent substrate is used for the liquid crystal display part, and thin plastic or film is used for the touch switch.
Materials that are as thin and light as possible are used.

[0009]

However, according to the above-mentioned conventional liquid crystal display device, when the touch switch (7) is crimped by the input pen (ST), the entire touch switch (7) is bent by the pressure at the time of input. Further, the pressure due to the deflection propagates to the liquid crystal (3) in the liquid crystal display section (4).

By the way, a normally white liquid crystal display panel is usually used for the liquid crystal display section (4), and when inputting with the input pen (ST) as shown in FIG. 5, it is at the position of the input point. The electric field is applied only to the liquid crystal molecules (3A), but the electric field is not applied to the liquid crystal molecules (3) in the region other than the input point. As a result, the force that regulates the molecular direction of the liquid crystal molecules (3) in the region other than the input point is only the alignment regulating force by the alignment film (not shown) formed on the transparent substrate. Since this alignment control force is relatively weak,
Liquid crystal molecules in the area near the input point are in the liquid crystal layer (3) during input.
Since the liquid crystal molecules in the vicinity of the input point are distorted by the pressure propagating up to, as shown in FIG.
There was a problem that the display was blurred at the time of input, and when it was terrible, the input characters and pictures were almost unreadable.

[0011]

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and as shown in FIG. 2, a point where pressure is applied from the upper surface (this point will be referred to as an input point hereinafter). )
, A liquid crystal layer is enclosed between the touch switch having a light-transmitting property, a first transparent substrate, and a second transparent substrate formed on the first transparent substrate. Becomes
The touch switch is provided below the touch switch, and has a liquid crystal display unit for displaying the position of the input point, and the liquid crystal display unit is a normally black type liquid crystal display panel, An electric field is constantly applied to the liquid crystal layer,
By displaying the input point by not applying an electric field selectively only to the liquid crystal layer corresponding to the area of the input point,
Minimize size while suppressing display bleeding due to input pressure
It is intended to provide a liquid crystal display device with an input device, which can be made thinner, lighter, and cheaper.

[0012]

[Operation] According to the liquid crystal display device of the present invention, as shown in FIG. 2, the liquid crystal display unit is a normally black type liquid crystal display panel, and the liquid crystal layer in the region other than the input point always has an electric field. Is applied and the electric field is not selectively applied only to the liquid crystal layer corresponding to the area of the input point, thereby displaying the input point.

For this reason, even if the touch switch (17) is slightly bent as a whole due to the crimping force at the time of input and the pressure is transmitted to the liquid crystal layer (13), the liquid crystal layer (1
An electric field is always applied to 3), and the liquid crystal layer (1
The input point is displayed by selectively not applying the electric field only to 3A). In addition to the alignment regulating force received from the alignment film, the liquid crystal molecules of the liquid crystal layer (13) in the region other than the input point always have a direction regulating force that acts so that the liquid crystal molecules are oriented in a certain direction by applying an electric field. Therefore, unlike the conventional device in which only the alignment regulating force acts on the liquid crystal molecules, the liquid crystal molecules in the region of the liquid crystal layer other than the input point are less likely to swing even if some pressure is applied.

Therefore, as in the prior art, since only the alignment regulating force received from the alignment film is applied to the liquid crystal molecules near the input point, the liquid crystal molecules around the input point easily oscillate due to the pressure and the liquid crystal It is possible to suppress blurring of the display near the input point on the display unit as much as possible.

[0015]

EXAMPLE A liquid crystal display device according to an example of the present invention will be described below. Note that FIG. 3 is a sectional view taken along line XX of FIG. A liquid crystal display device according to an exemplary embodiment of the present invention is 320
A display having a display capacity of × 240 dots, and as shown in FIG. 1, first and second transparent substrates (11, 11) having predetermined members such as transparent electrodes and alignment films (not shown) formed on the surface thereof. 12) is fixed by the sealing material (S1),
A liquid crystal display (1) in which a liquid crystal (13) is sealed in between
4) and the third and fourth transparent substrates (15, 16), which are electrodes of the touch switch and have an electrically conductive ITO film (not shown) attached to one surface of the transparent substrate, respectively. The analog input type of the fourth transparent substrate (16) is disposed on the third transparent substrate (15) via the spacer (S2) so that the adhered ITO (Indium Tin Oxide) films face each other. Resistive Touch Switch (17)
Have and.

The touch switch (17) is formed on the liquid crystal display (14) to save space.
The liquid crystal display (14) has a normal black STN
A liquid crystal panel is used, and a polarizing plate (20) is also attached to the lower part of the liquid crystal display section (14). Furthermore, the polarization direction of the polarizing plate (19) and the polarization direction of the polarizing plate (20) match.

According to this apparatus, a pattern such as a character or a picture is manually input on the fourth transparent substrate (16) above the touch switch (17) with an input pen (ST) having a tip with a radius of 1 mmφ. By doing so, the input pattern can be displayed on the liquid crystal display section (14) below the touch switch (17), so that the operator can display the input pattern via the touch switch (17) having translucency. You can input while watching.

That is, the operator crimps a desired point on the fourth transparent substrate (16) which is the upper substrate of the touch switch (17) with the input pen (ST). Then, the third
The transparent substrate (15) and the fourth transparent substrate (16) come close to each other due to the pressure at the time of input, and the ITO films (not shown) serving as electrodes formed facing each other on both sides thereof come into contact with each other.

This ITO film is formed on the third and fourth transparent substrates (1
5, 16) are evenly formed on the entire surface of the input pen (S
The upper and lower ITO at the input point, which is the point crimped by T)
When the films contact each other, the current between the upper and lower ITO films changes. Since this current change differs for each input point, the position of the input point is detected by detecting this current change.

When the position of the input point thus detected is output to a drive circuit (not shown), an electric field is applied only to the liquid crystal molecules (13A) at the position of the input point as shown in FIG. Since the electric field is applied to the liquid crystal molecules (13) in other regions, the liquid crystal molecules (13) at the input point
Only A) is in the twisted orientation state. Therefore, the polarizing plates (18, 19) provided above and below the liquid crystal display section (14)
Have the same polarization direction, and in the normally black liquid crystal display unit (14), the liquid crystal molecules (1
Since only 3A) is in the twisted alignment state, black dots are displayed only on the liquid crystal display portion (14) at the position of the input point.

When an input pattern such as a line, a character, or a picture is input by repeating the above operation for each input point, the pattern is displayed on the liquid crystal under the touch switch (18) as shown in FIG. The touch switch (1) which can be displayed in black on the part (17) and has a light-transmitting property.
The operator can confirm this display through 8).

As described above, according to the liquid crystal display device of the present embodiment, as shown in FIG. 1, the liquid crystal display section is a normally black (negative) type liquid crystal display panel,
The input point is displayed by always applying the electric field to the liquid crystal layer (13) in the area other than the input point and selectively not applying the electric field only to the liquid crystal layer (13A) corresponding to the area of the input point.

For this reason, even if the touch switch (17) is slightly bent as a whole due to the crimping force at the time of input, and the pressure is transmitted to the liquid crystal layer (13), the touch switch (17) does not reach the liquid crystal layer (13) in the region other than the input point. Displays the input point by always applying the electric field and not selectively applying the electric field only to the liquid crystal layer (13A) in the area of the input point. Therefore, the liquid crystal molecules of the liquid crystal layer (13) other than the input point are applied with an electric field in addition to the alignment regulating force received from the alignment film (not shown) formed so as to contact the liquid crystal layer (13) at the top and bottom. Due to this, the direction-regulating force that works so that the liquid crystal molecules face a certain direction is constantly applied, so unlike the conventional device in which only the alignment-regulating force acts on the liquid crystal molecules, even if some pressure is applied The liquid crystal molecules of the liquid crystal layer (13) in the area are less likely to swing.

As a result, as in the prior art, only the alignment regulating force received from the alignment film (not shown) is applied to the liquid crystal molecules near the input point, so that the liquid crystal molecules (13) around the input point can be easily pressurized. It is possible to prevent the display near the input point of the liquid crystal display unit (14) from swinging and blurring as much as possible. Therefore, there is almost no blurring of the display, and the size is reduced,
It becomes possible to obtain a liquid crystal display device with an input device, which is thin and lightweight, and is particularly effective when the liquid crystal display device is mounted on a PDA or the like.

Further, although the analog input resistive film type touch switch is used in the present embodiment, the present invention is not limited to this, and any input device such as a pen input which is input by pressing is used. Therefore, the same effect can be obtained with any input device.

[0026]

As described above, according to the liquid crystal display device of the present invention, the liquid crystal display unit is a normally black type liquid crystal display panel, and the liquid crystal layer in the area other than the input point is always provided with an electric field. Is applied and the electric field is not selectively applied only to the liquid crystal layer corresponding to the area of the input point, thereby displaying the input point.

For this reason, even if some pressure is applied during input, the liquid crystal molecules around the input point are less likely to oscillate. Therefore, as in the conventional case, only the alignment regulating force received from the alignment film is in the vicinity of the input point. Since it is added to the molecule, it is possible to prevent liquid crystal molecules around the input point from easily swinging due to pressure and blurring the display near the input point of the liquid crystal display unit.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating an operation of the liquid crystal display device according to the embodiment of the present invention.

FIG. 3 is a top view illustrating an operation of the liquid crystal display device according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a liquid crystal display device according to a conventional example.

FIG. 5 is a cross-sectional view illustrating an operation of a liquid crystal display device according to a conventional example.

FIG. 6 is a top view for explaining the operation of the liquid crystal display device according to the conventional example.

FIG. 7 is a diagram illustrating a conventional problem.

[Explanation of symbols]

 (11) First transparent substrate (12) Second transparent substrate (13) Liquid crystal (13A) Liquid crystal molecule at input point (14) Liquid crystal display section (15) Third transparent substrate (16) Fourth transparent substrate (17) Touch switch (18) Polarizing plate (19) Polarizing plate (S1) Sealing material (S2) Spacer (ST) Input pen

Claims (2)

[Claims] 1. A touch switch which detects a position of a point (hereinafter referred to as an input point) to which pressure is applied from the upper surface and has a light-transmitting property, a first transparent substrate, and a first transparent substrate. A liquid crystal layer is provided between the second transparent substrate formed on the first transparent substrate and the liquid crystal display unit, which is provided below the touch switch and displays the position of the input point. The liquid crystal display section is a normally black type liquid crystal display panel, and an electric field is constantly applied to the liquid crystal layer in the area other than the input point, and only the liquid crystal layer corresponding to the area of the input point is applied. A liquid crystal display device, wherein the input point is displayed by selectively not applying an electric field. 2. The touch switch includes a third transparent substrate having a transparent electrode formed on the surface thereof, and a fourth transparent substrate having a transparent electrode formed on the surface thereof. The liquid crystal display device according to claim 1, wherein a surface of the liquid crystal display device faces the fourth transparent substrate.